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Monitoring the penetration process of single microneedles with varying tip diameters

Monitoring the penetration process of single microneedles with varying tip diameters
Monitoring the penetration process of single microneedles with varying tip diameters
Microneedles represent promising tools for delivery of drugs to the skin. However, before these microneedles can be used in clinical practice, it is essential to understand the process of skin penetration by these microneedles. The present study was designed to monitor both penetration depth and force of single solid microneedles with various tip diameters ranging from 5 to 37 µm to provide insight into the penetration process into the skin of these sharp microneedles. To determine the microneedle penetration depth, single microneedles were inserted in human ex vivo skin while monitoring the surface of the skin. Simultaneously, the force on the microneedles was measured. The average penetration depth at 1.5 mm displacement was similar for all tip diameters. However, the process of penetration depth was significantly different for the various microneedles. Microneedles with a tip diameter of 5 µm were smoothly inserted into the skin, while the penetration depth of microneedles with a larger tip diameter suddenly increased after initial superficial penetration. In addition, the force at insertion (defined as the force at a sudden decrease in measured force) linearly increased with tip diameter ranging from 20 to 167 mN. The force drop at insertion was associated with a measured penetration depth of approximately 160 ?m for all tip diameters, suggesting that the drop in force was due to the penetration of a deeper skin layer. This study showed that sharp microneedles are essential to insert microneedles in a well-controlled way to a desired depth.
skin mechanics, microneedle, penetration force, penetration depth
1751-6161
397-405
Römgens, A.M.
9beb720f-010f-478b-961c-2dca02a6c8af
Bader, D.L.
9884d4f6-2607-4d48-bf0c-62bdcc0d1dbf
Bouwstra, J.A.
03b17e4c-0051-49f5-8a2e-a041aabdd9f8
Baaijens, F.P.T.
5d9e63e2-7d7b-4f64-b942-29121121dce0
Oomens, C.W.J.
a8310c52-8ab4-4652-b2d6-82269a3c7438
Römgens, A.M.
9beb720f-010f-478b-961c-2dca02a6c8af
Bader, D.L.
9884d4f6-2607-4d48-bf0c-62bdcc0d1dbf
Bouwstra, J.A.
03b17e4c-0051-49f5-8a2e-a041aabdd9f8
Baaijens, F.P.T.
5d9e63e2-7d7b-4f64-b942-29121121dce0
Oomens, C.W.J.
a8310c52-8ab4-4652-b2d6-82269a3c7438

Römgens, A.M., Bader, D.L., Bouwstra, J.A., Baaijens, F.P.T. and Oomens, C.W.J. (2014) Monitoring the penetration process of single microneedles with varying tip diameters. Journal of the Mechanical Behavior of Biomedical Materials, 40, Winter Issue, 397-405. (doi:10.1016/j.jmbbm.2014.09.015).

Record type: Article

Abstract

Microneedles represent promising tools for delivery of drugs to the skin. However, before these microneedles can be used in clinical practice, it is essential to understand the process of skin penetration by these microneedles. The present study was designed to monitor both penetration depth and force of single solid microneedles with various tip diameters ranging from 5 to 37 µm to provide insight into the penetration process into the skin of these sharp microneedles. To determine the microneedle penetration depth, single microneedles were inserted in human ex vivo skin while monitoring the surface of the skin. Simultaneously, the force on the microneedles was measured. The average penetration depth at 1.5 mm displacement was similar for all tip diameters. However, the process of penetration depth was significantly different for the various microneedles. Microneedles with a tip diameter of 5 µm were smoothly inserted into the skin, while the penetration depth of microneedles with a larger tip diameter suddenly increased after initial superficial penetration. In addition, the force at insertion (defined as the force at a sudden decrease in measured force) linearly increased with tip diameter ranging from 20 to 167 mN. The force drop at insertion was associated with a measured penetration depth of approximately 160 ?m for all tip diameters, suggesting that the drop in force was due to the penetration of a deeper skin layer. This study showed that sharp microneedles are essential to insert microneedles in a well-controlled way to a desired depth.

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More information

Accepted/In Press date: 15 September 2014
e-pub ahead of print date: 8 October 2014
Published date: December 2014
Keywords: skin mechanics, microneedle, penetration force, penetration depth
Organisations: Faculty of Health Sciences

Identifiers

Local EPrints ID: 373454
URI: http://eprints.soton.ac.uk/id/eprint/373454
ISSN: 1751-6161
PURE UUID: 08a89c8e-a3aa-4e53-ac99-d1ea2ca8f325
ORCID for D.L. Bader: ORCID iD orcid.org/0000-0002-1208-3507

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Date deposited: 20 Jan 2015 11:16
Last modified: 14 Mar 2024 18:53

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Contributors

Author: A.M. Römgens
Author: D.L. Bader ORCID iD
Author: J.A. Bouwstra
Author: F.P.T. Baaijens
Author: C.W.J. Oomens

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